During some surgical methods it is desirable or necessary to staple tissues together. In particular, it can be necessary to staple the ends of two closed tubes in the body together to form one tube. This may be the case where a section of a tube (such as a section of the gastrointestinal tract, which includes the oesophagus, stomach, duodenum, jejunum, ileum, colon and rectum) has been removed from the body. This may have occurred for instance when cancerous tissue is removed. The tube either side of the removed section is typically closed, for example by staples or stitches. After the section of the tube is removed, it is necessary to join the two closed portions of the tube together.
A prior art example of a stapler designed to join to tube portions together is shown in FIG. 1. This shows a prior art stapler 1 and anvil 20 that are used to connect two tubes of the body together. The stapler 1 is inserted into a tube 10 from a proximal end 12. The anvil 20 is inserted into a tube 11 from the distal end 13. Thus, to staple the two tubes 10, 11 together, access is required from two sides 12, 13.
During stapling, the anvil 20 and the stapler 1 are pressed toward each other. This draws the closed ends 14, 15 of the two tubes 10, 11 towards each other. When the anvil 20 presses against stapler 1, and the tissue of the ends 14, 15 of the tubes 10, 11 are effectively clamped between the stapler 1 and the anvil 20, the stapler 1 can fire staples toward the anvil 20 and hence through said tissue. The anvil 20 provides resistance to said staples and hence aids in their folding. Once folded, the staples hold the two tubes 10, 11 together. The stapler 1 and anvil 20 are circular and produce a double concentric ring of staples.
The stapler 1 comprises a circular knife edge (not shown) that is then pressed against the anvil 20 inside the ring of staples. This cuts through the ends 14, 15 of the tubes 10, 11, thus forming a path between the tubes 10, 11. The stapler 1 is then removed from the proximal end 12 and the anvil is also removed from the proximal end 12. The anvil 20 is first tilted and then pulled through the path between the tubes 10, 11.
As can be appreciated, this method requires access from both the proximal end and the distal end to the region to be stapled.
Various proposed alternatives to the standard prior art technique of FIG. 1 are disclosed in US 2015/0327853. In some embodiments, this document discloses a surgical stapler that can be inserted and operated from only the proximal end. This is achieved by the surgical stapler comprising an anvil whose area can be decreased when being inserted through the tissue to be stapled and when being retracted through the tissue after stapling and whose area can be increased during the stapling operation to provide resistance to the staples. An ‘umbrella’ type collapsing mechanism is used. However, the decreased area is still relatively large and it is therefore difficult to insert the anvil through the tissue to be stapled, and the anvil can cause damage to the staples when it is retracted through the stapled tissue. In other embodiments of US 2015/0327853 the collapsing mechanism involves a folding disc or segments of a ring that join together to form the anvil, which allows for a smaller size for the folded anvil. However, in those cases there is a requirement for access to the anvil from the distal end, i.e. beyond the stapling location, which complicates the surgical procedure, and there is in some cases no straightforward way to collapse the anvil after use, which means that the risk of damage to the stapled tissue is no lower than for the conventional anvil FIG. 1.